How can I become a world-class coder in under three years?

Build your own blogging engine. Next, try to design and write the One True CMS (you’ll fail just like thousand of others have before you, but you’ll learn lots in the process).

Build your own todo list software. Now expand it to be your own email client. Extend it to support plugins. Now invent your own scripting language for writing plugins in, and write your own interpreter for it.